AT A GLANCE, getting good sleep seems pretty straightforward. Get (roughly) 8 hours of sleep every night. Check. Make sure nothing is waking you up in the middle of the night. Double check. But as you go down your checklist, have you crossed off what should be item number one? It turns out there’s a third sleep factor people are ignoring and it could be silently wrecking your heart.
A 10-year investigation published in BMC Cardiovascular Disorders discovered that people between the ages of 40 to 60 who went to bed at varying times each night were more likely to have heart problems than those with a consistent bedtime schedule. Before you tuck in, make sure to read this.
What Did the Study Find?
THE RESEARCHERS TRACKED the sleep and wake-up times of 3,231 people (all of them were age 46 at the start) to get an idea of their usual bedtime schedules. They spent the next ten years combing through the medical records of each person to monitor the trajectory of their health.
During those 10 years, 128 people experienced a major heart event—events ranged from unstable angina, stroke, and heart failure to cardiac-related death. After controlling for factors like BMI and cholesterol, the common denominator among this group was that their bedtimes were all over the place.
The risk for heart problems was doubled in people who had a shifting sleep schedule and received less than eight hours a night. Meanwhile, waking up at different times of the day did not make a difference in heart risk.
“Our findings suggest that the regularity of bedtime, in particular, may be important for heart health. It reflects the rhythms of everyday life and how much they fluctuate,” says Laura Nauha, PhD, postdoctoral researcher at the University of Oulu and lead study author.
Why is a Consistent Bedtime Important for Heart Health?
SLEEP IS GOVERNED by a circadian rhythm, a biological clock that optimizes the timing of your bodily functions. This ‘clock’ works on a roughly 24-hour schedule and is behind when your body decides it’s time to eat, rest, and wake up. Sudha Tallavajhula, MD, neurophysiologist and sleep medicine specialist at UTHealth Houston, explains that the circadian rhythm is also in charge of hormone fluctuations, heart rhythms, and blood pressure—all of which factor into a healthy heart.
When you continue to change your bedtime, it disrupts your circadian rhythm, says Grant Bailey, MD, cardiologist at South Denver Cardiology and AdventHealth Littleton.
What does that look like to your heart? Stress hormones and adrenaline increase, which can affect heart rate and blood pressure. Hunger hormones can fluctuate, leading to poor food choices. With continued sleep deprivation, the risk of anxiety and depression rises, which may indirectly further heart strain.
Most importantly, Dr. Tallavajhula says the shift in metabolic efforts from movement and digestion to repair, hormonal regulation, and memory consolidation all happens during sleep. This housekeeping mode is necessary for recovery of the heart and the brain. “Poor sleep keeps the heart under consistent stress and does not allow for recovery time. We understand now that all three aspects of sleep: quality, quantity, and timing of sleep all are equally import